Paper feed regulating assembly for presses and duplicators

ABSTRACT

A paper feed regulator assembly which includes a microswitch having as a portion thereof, an overriding spring plate. A bar is provided to act as a cantilever support in mounting the microswitch on a duplicator or press above a vertically reciprocable feed table forming a part thereof. An electrically actuated solenoid is mountable on the duplicator or press by suitable means provided for this purpose, and a pawl latch lever is interconnected with the armature of the solenoid by a linkage such that when the solenoid is activated, the armature of the solenoid is pulled in, and the pawl latch lever engages a pawl lever to prevent further incremental elevation of a paper feed table included in the duplicator or press. The assembly further includes electrical circuitry in which is located the microswitch and coil of the solenoid, along with an appropriately actuated indicator light for indicating the status of the paper feed regulating assembly.

United States Patent Stanfield [Ill 3,921,970

[ l Nov. 25, [975 Jay E. Stanfield, PO. Box 333, Guymon Okla, 73942 {22] Filed: May 31,1974

[Zll Appl. No: 474.975

(76] Inventor:

[52] U.S. Cl. l t a t v ..271/}1;27l/l()7;27l/l7l; 27l/l54 [Sll Int. CL U... H HfiSH 1/14; B65H 3/08 [58I Field of Search t i. Z7l/3U R, 1|,90, 98,103 27l/IU7v Hi8, l52. I53, l54. I55, 156. l7l

(Sol References Cited UNITED STATES PATENTS 2,282,224 5/l942 Harrold, t r i r i r 27l/98 2.739 8lO 3/1956 Miller v v i .r 27l/l55 3580.567 5/l97l Hashimotom. 27l/l54 3,655183 4/l972 Wagner i s 27l/l55 3v7S4i75l EH97 Capcttt ct ali. t l l i l r r i, Z7l/l03 Primary E.raminerEvon C Blunk Axsisiunr E.ramincrRobe rt Saifer Attorney Agent. or FirmLaney, Dougherty, Hessin & Fish [57] ABSTRACT A paper feed regulator assembly which includes a mi croswitch having as a portion thereot". an overriding spring plate. A bar is provided to act as a cantilever support in mounting the microswitch on a duplicator or press above a vertically reciprocable l'eed table forming a part thereof An electrically actuated solenoid is mountable on the duplicator or press by suitable means provided for this purpose, and a pawl latch lever is interconnected with the armature ol the sole noid by a linkage such that when the solenoid is activated, the armature of the solenoid is pulled in, and the pawl latch lever engages a pawl lever to prevent further incremental elevation of a paper feed table included in the duplicator or press, The assembly fur ther includes electrical circuitry in which is located the microswitch and coil of the solenoid, along with an appropriately actuated indicator light for indicating the status of the paper feed regulating assembly.

35 Claims, 13 Drawing Figures US. Patent Nov. 25, 1975 Sheet 1 U.S. Patent Nov. 25, 1975 Sheet 2 of3 3,921,970

PAPER FEED REGULATING ASSEMBLY FOR PRESSES AND DUPLICATORS BACKGROUND OF THE INVENTION l. Field of the Invention This invention relates to systems and assemblies utilized on duplicating machines or printing presses for the purpose of controlling the feed of sheets of paper. envelopes or the like from a stack of such materials carried on a vertically reciprocable feed table.

2. Brief Description of the Prior Art A number of types of systems have heretofore been provided for sensing and controlling relatively thin sheets of material being fed one by one and in sequence from the top of a stack of such materials located on a vertically moving feed table. In this broad category of devices are certain types of duplicating machines and printing presses in which individual sheets of paper or envelopes or similar paper structures in flat sheet form are fed through a portion of the apparatus to imprint or mark the sheets in individual sequence. In such machines, mechanism is conventially provided for incrementally elevating the feed table upon which the stack of sheets to be fed through the machine is located so that as the sheets at the top of the stack are removed therefrom. and fed in sequence to the press or duplicator, the feeding mechanism which picks up each sheet will remain properly positioned and properly functioning in relation to the following sheets which continue to be made available to such feeding mechanism.

A problem which has been recognized to exist in optimizing the feeding of individual sheets of paper. and envelopes or the like into presses and duplicators from a feed table which is periodically elevated in incremental movements, is that of continuing to provide the right type of frictional contact between the top sheet of the stack and the fingers, vacuum cups or rollers which move the top sheet off the stack into the duplicating machine. It is also known to be important that the particular geometric position of the top sheet which is to be fed, in relation to the feeding elements of the apparatus, be near optimum in order to facilitate feeding without jamming or wrinkling or distortion of the sheets.

To the end of improving and optimizing the feeding systems of duplicators and presses of the type described, various types of sensing or feeling devices have been provided adjacent the level of the top of the stack of sheets to be fed, with such structures functioning to sense the positioning of the top sheet at an optimum location, and to generate a mechanical or electrical signal to which the mechanism used to activate and elevate the feed table is made responsive. Two systems of this type are those which are shown in U.S. Pat. Nos. 3.655.183 to Wagner, and 3,580,567 to Hashimoto.

In the Wagner system. a motor driven cam is utilized for incrementally raising a feed table for purposes of supplying paper to duplicating machines. Due to the inherent limitation imposed by the cam travel in this system. elevation of the feed table adequately for use in printing presses of the type which include stacks of paper extending to heights of 24 inches or more is not feasible. In other words, the Wagner system appears to be employed primarily in association with office copiers and duplicators where the paper tray or table need not move more than a very few inches during its travel. The Wagner system employs a sensing wheel mounted 2 in the duplicator or copier so as to ride upon the top sheet of paper in the paper stack and. through suitable electrical circuitry. to drive the cam and elevate the paper table at appropriate times.

In Hashimoto US. Pat. No. 3,580,567. there is provided a small sensing roller positioned for contact with the top of the paper stack and able to rise and fall in response to the changing level of the top of the stack so as to actuate a microswitch by such movement. The microswitch is connected to a solenoid which is connected to a mechanical linkage which controls the elevation of the paper table employed for elevating the stack of paper. The system operates by maintaining the paper stack against a friction type forwarding roller used to feed the paper into the photocopy machine or printing press. Although the Hashimoto system endeavors to maintain a constant upward pressure under the forwarding roller, it is not possible. in fact. to maintain such constant pressure, because the incremental movement of the feed table is represented by the throw involved in the movement of one tooth increment on the actuating ratchet wheel. The length of this throw will cause some variations in pressure as the ratchet wheel is rotated to elevate the feed table. Further, the sensing roller utilized in the Hashimoto system exerts a significant downward pressure on the upper sheet of paper. causing an unacceptably high amount of friction between the first and second sheets of paper tending to cause feeding problems.

Although most systems which have developed work adequately in situations in which plain sheets of paper of a certain bond or weight are to be fed to printing presses or to a duplicating or copying machine, difficulty continues to be experienced with many of the duplicating machines when it is attempted to feed materials such as envelopes. or any highly compressible paper stock. such as cockle finish onionskin. The compressibility of these stocks renders the sensing systems previously provided either insufficiently sensitive. or erratic in sensing. so that they cannot be depended on to assure a smooth and trouble free feed into the duplicator of these types of paper materials.

BRIEF DESCRIPTION OF THE PRESENT INVENTION The present invention is directed to an improved. highly effective system or assembly for regulating the feed of sheets of paper from a stack of sheets on a vertically reciprocating feed table into a printing or duplicating apparatus. The assembly is especially useful in the feeding of envelopes, compressible papers or paper articles which are of varying thickness from one side thereof to the other.

Broadly described, the present invention is an electromechanical feed regulating assembly which comprises a sensitive microswitch sub-combination which contains a contact spring plate able to yield and override the switch closure position, a solenoid actuated upon closure of the microswitch. a mechanical feed arresting subassembly connected to the armature of the solenoid for interrupting the upward movement of the paper feed table when the solenoid is actuated, and electrical circuitry interconnecting the coil of the solenoid and the microswitch. and including an indicator light which provides an ON-OFF indication of whether this system is in a feed or interrupt feed" status.

In a preferred embodiment of the invention. the paper feed regulating assembly of the present invention, as broadly described above, is further employed in combination with airjet elements mounted on the press or duplicator in association with the microswitch sensing element, and functioning to prevent excessive static electricity adherence of the sheets of paper to each other at the upper side of the stack from which the paper sheets are being fed to the machine. The preferred embodiment of the invention further includes a plurality of gravity actuated floating vacuum heads provided for the purpose of picking up the top sheet of paper. and feeding this paper into the press or duplicator. Finally, centering plates having a novel clamp and slide structure for quickly mounting on various types of cross bar supporting structures provided in presses and duplicators afford a further improvement to the paper guidance and regulating system of the present invention.

From the foregoing brief description of the present invention, and from the description which will hereinafter follow, it will become apparent that an important object of the present invention is to provide a very sensitive and effective system for regulating the feed of sheets of paper. envelopes and other paper stock articles from a vertical stack of such materials into a printing press or duplicating machine.

A more specific object of the invention is to provide a sensitive microswitch including system which functions by limiting the paper feed table from elevating, by incremental movement. to an excessive height.

Another object of the invention is to provide an electromechanical system with a sensitive touch" to the elevation of paper on a paper feed table included in a press or duplicator system, which electromechanical system can function alternatively to, or in conjunction with, a mechanical sensing system provided by the manufacturer on such presses or duplicators.

Another object of the present invention is to provide an improved system for sensing the height of paper stacked on a paper feed table in a press or duplicator, and for controlling the movements of such paper feed table without interfering with airjets provided in some types of duplicators and presses employing such paper feed tables.

An additional object of the invention is to provide a paper feed regulating assembly which can be employed for regulating the feed of sheets of paper from stacks of such sheets carried on a feed table, and having a stack height of from 2 inches to as high as 24 inches without malfunction or a loss of efficiency.

An additional object of the invention is to provide an improved vacuum head pick-up system for lifting and feeding the top sheet of paper in a stack of paper sheets carried on the feed table of a duplicator or printing press.

An additional advantage of the present invention is that of including within an improve paper feed regulating assembly, a visual indication to an operator of when the assembly is controlling the feed mechanism of a press or duplicator in such way that paper is being fed, or the assembly is preventing the feeding of paper.

Yet another object of the invention is to provide a sturdily constructed. inexpensive and efficiently functioning paper feed regulating assembly which can be quickly and easily installed on most existing duplicating machines and printing presses using a vertically reciprocating feed table. for accurately and precisely controlling the feed of individual paper sheets carried in a stack on such feed table.

Additional objects and advantages of the present invention will becoorne apparent from the following detailed description ofa preferred embodiment of the invention when the same is considered in conjunction with the accompanying drawings which illustrate the invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a top plan view of one type of duplicating machine having the paper feed regulating assembly of the present invention mounted thereon.

FIG. 2 is a detail view in side elevation of one of the mechanical sensing fingers previously used in some types of duplicating machines.

FIG. 3 is an enlarged sectional view taken along line 33 of FIG. 1.

FIG. 4 is a sectioal view taken along line 44 of FIG. 3.

FIG. 5 is a view partly in section and partly in elevation illustrating the improved clamp element associated with an improved center plate employed in the paper feed regulating assembly of the present invention.

FIG. 6 is an end elevation view ofthe structure shown in FIG. 5.

FIG. 7 is a bottom plan view of the structure shown in FIG. 5.

FIG. 8 is a view in elevation, with a portion broken away, of a gravity actuated floating vacuum head assembly of one type used in the paper feed regulating assembly of the present invention.

FIG. 9 is a vertical sectional view through the center of a different embodiment of vacuum head assembly which can be used in the present invention.

FIG. 10 is a view in elevation illustrating the manner in which a solenoid forming a portion of the present invention is adapted for securement to a side of a duplieating machine in which the paper feed regulating assembly of the invention is to be mounted.

FIG. 11 is an electrical circuit diagram showing the circuitry containing the microswitch, light and solenoid used in the paper feed regulating assembly of the invention.

FIG. 12 is a side elevation view of certain details of structure forming a part of the paper feed regulating assembly of the present invention, and showing such structure in its status in which it is engaged with structural parts of the duplicating machine to prevent further incremental elevation of a paper feed table forming a part of the duplicating machine.

FIG. 13 is a view similar to FIG. 12 except illustrating the structure in a status in which the paper feed regulating assembly of the present invention is disconnected or released from the mechanism used for incrementally raising the paper feed table in a duplicator of the type under discussion.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION Referring initially to FIG. I of the drawings. shown therein is a base housing I0 which has mounted thereon a framework superstructure I2 which includes a pair of vertically extending side plates I4. For simplication of explanation and better understanding of the present invention, all auxiliary and ancillary structure which are conventionally mounted in the base housing or on the framework superstructure have not been illustrated in FIG. I or the remainder of the drawings of this application. except so much of the structure as is involved in the operation of the present invention. and as is necessary to an understanding of the present invention. It will be understood by those skilled in the art that on many types of duplicators. of which the one illustrated in the figures is typical, the base housing includes a paper storage zone, and a paper feed table which has a horizontally extending upper surface for supporting a stack of paper sheets, and which is elevated in increments by appropriate mechanism at proper times to assure continuous feed of the paper to the duplicating portion of the apparatus. A feed table of this general type is represented in FIG. I by the schematically illustrated structure 16, and a stack of paper sheets carried thereon is shown by the reference character 18. It may be further pointed out, by way of explanation, that the printing rolls and duplicating apparatus per se are generally located just to the left of that structure illustrated in FIG. 1 and are mounted by suitable supporting shafts and brackets in the framework superstructure. The printing and duplicating structure per se forms no part of the present invention. which is concerned with the paper feed regulating assembly used for feeding paper from the stack of paper sheets 18 into the printing and duplicating mechanism.

Adjustably mounted between the vertically extending side plates 14 is a horizontally extending U-shaped supporting bracket 20 which includes parallel arms 20a and 20b and a transversely extending slide bar 20c. Slidably mounted on the slide bar 20c by means of an improved clamp structure 22 are a plurality of elongated plates 24, 26 and 28.

The construction of each clamp structure 22 is best illustrated in FIGS. 3-7 of the drawings. In referring to these figures of the drawing, it will be perceived that each clamp structure 22 includes a generally U-shaped housing element 30 having a head space 32 formed in the upper side thereof, and having a pair of elongated slots 34 formed in the opposite sides thereof near the lower edges of these opposite sides. Each of the slots is undercut so as to receive and retain one of the elongated plates 24, 26 or 28. A pressure plate 38 is secured to the lower end of the shaft 40 of a bolt 42 and a biasing helical spring 44 is disposed around the shaft between the top of the U-shaped housing element 30 and the pressure plate 38. Secured to the opposite sides of the U-shaped structure 30 on the inner side thereof are a pair of high density, synthetic resin blocks 46 and 48 which are spaced from each other to accommodate the slide bar 20c, and are preferably constructed ofa material having a relatively low coefficient of friction. It will be noted in referring to FIG. 3 that the blocks 46 and 48 have their lower edges terminating flush with the upper side of the slots 34 formed in the sides of the U- shaped structure 30.

It will be perceived from the description of the clamp structures 22 that a friction clamp is provided which permits manual sliding of the friction clamps and the elongated plates 24-28 carried thereby transversely along the slide bar 20c to a selected position therealong, as may be desired by the operator of the printing or duplicating apparatus. Moreover, the elongated plates 24-28, whose function and purpose will hereinafter be described, can be quickly and easily inserted through the elongated slots 34 provided near the lower edges of the sides of the clamp structures 20 by merely sliding the free end of these plates through these slots at a time when the U-shaped structure 30 has been pushed downwardly relative to the slide bar 200 so as to expose the slots and permit the plates 24-28 to he slid through the respective slots 34 in the respective clamp structure 22.

In the conventional duplicating and printing machines in which the paper feed regulating assembly of the present invention is incorporated, the elongated plates 24-28 are used to carry paper backstep or guide structures which function to maintain the alignment of the sheets of paper included in the stack 18. An improved backstep structure for accomplishing this function is generally indicated by reference numeral 52 in FIGS. 5-7. It will be perceived that the backstep structure includes an arcuate pressure plate 54 of spring metal, and an L-shaped supporting plate 56 which has its lower leg 56a secured to the lower end of the arcuate pressure plate. ln the improved structure of the present invention, the upper leg 56b of the L-shaped supporting plate 56 projects horizontally, and is retained in abutting contact with the lower side of one end portion of an elongated plate of the type typified by the plates 24-28 shown in FIG. I. The upper leg 56b of the L-shaped supporting plate is provided with a pair of apertures 560 which fit over, and mate with, a pair of hemispherical protuberances 58 secured on the lower side of the respective plate 24-28. A bolt 60 is threaded into the lower side of the respective plate 24-28 through a hole formed in the upper leg 56b of the L- shaped supporting plate and a helical compression spring 62 is disposed around the shank of this bolt and bears against the upper leg of the supporting plate.

With this arrangement, it will be perceived that by pulling down on the backstep 52 against the pressure of the spring 62, the upper leg 56b of the L-shaped supporting plate 56 can be disengaged from the hemispherical protuberances 58 to allow the backstep 52 to be pivoted through 180 and then reseated on the hemispherical protuberances 58 after it comes to occupy the position depicted in dashed lines in FIG. 5. This arrangement allows the direction of extension of any one of the plates 24-28 to be reversed so that much longer sheets of paper in the stack 18 can be accommodated. The accommodation is, of course, as previously indicated, in the form of allowing the baeksteps 52 to bear against a vertical side of the stack of paper sheets 18 to retain the stack in verticality, and the sheets aligned. It should also be noted that the back step 52 can be placed in a position at 90 from the full line and dashed line positions shown in FIG. 6 by pulling down on the back step and rotating it until the upper leg 56b of the L-shaped supporting plate 56 passes between and bears at its side edges against the hemispherical protuberances 58. This type of 90 arrangement is utilized for placing the back step 52 on an outer one of the plates 24-28 in a position of guidance and contact with the vertical side edge of the stack of paper sheets 18.

In the embodiment of the invention illustrated in the drawings, the elongated plate 24 has been modified at its free end positioned inwardly within the framework super-structure 12 to support a microswitch assembly constructed in accordance with the present invention. The relationship between the microswitch assembly 70 and the plate 24 is best illustrated in FIGS. 3 and 4 of the drawings. In referring to these figures, it will be noted that the microswitch assembly 70 includes a hollow housing 72 having a light aperture 74 formed at the upper side thereof, and enclosing a microswitch 76 having a downwardly facing contact 78. A light 80 is included in the circuitry with the microswitch 76 in a 7 manner hereinafter described, and is positioned immediately below the light aperture 74.

The lower side of the housing 72 is closed by means of a closure plate 82, which closure plate has an aperture 84 near one end thereof for accommodating a contact screw 85, and which has a spring plate retainer toe 86 pressed out of the other end thereof. The spring plate retainer toe 86 extends through a slot formed in a spring plate 88 which is mounted flatly on the upper side of the closure plate 82. The spring plate 88 has welded or otherwise suitably secured to the upper side thereof, a nut 90 which receives the threaded shank of the contact screw 85. In order to retain the adjustable contact screw 85 at its selected position of adjustment in relation to the spring plate 88, a friction finger 92 is loaded in resilient deformation against the side of the adjustable contact screw. and has one end secured to the upper side of the spring plate 88 in the manner depicted in FIG. 3.

Projecting from one side of the housing 74 is a mounting flange 96 which is apertured to facilitate the securement of this flange to the free end of the plate 24 by means of suitable screws 98.

Rotatahly mounted within the framework superstructure 12 and extending between the side plates 14 is an elongated tubular air manifold conduit 100. The air manifold conduit 100 is rotatable by suitable and conventional mechanism (not shown) about its longitudinal axis, and functions to provide communication between a plurality of novel floating vacuum heads 102, constructed in accordance with the present invention, and a source of vacuum (not shown).

The construction ofone of the floating vacuum heads 102 is illustrated in detail in FlG. 8 of the drawings. Thus. it will be perceived that the floating vacuum head includes a threaded neck portion 104 adapted to be threaded into a threaded receiving orifice formed in the air manifold conduit 100. A tubular body 106 projects downwardly from the threaded neck 104 and has an annular, radially inwardly extending flange 108 formed at the lower end thereof. Reciprocably disposed within the tubular body 106 for floating movement therein, and reciprocating actuation by gravity, is a sucker tube 110 having a suction cup 112 constructed of rubber. or other elastomeric material. on the lower end thereof. The sucker tube 110 has a movement limiting annular flange 113 formed around the upper end thereof for engagement with the flange 108 to limit the downward travel ofthe sucker tube. and prevent it from falling out of the tubular body 106. It will be noted in referring to FIG. 6 that a very slight clearance exists between the annular flange 113 and the tubular body 106, as well as between the flange 108 and the sucker tube 110. The manner of use and operation of the floating vacuum heads 102 for picking up and moving sheets of paper into the printing or duplicating mechanism will be here inafter explained in greater detail.

A different embodiment of a floating vacuum head which can be used to advantage in the paper feed regulating assembly of the present invention is illustrated in FIG. 11 In this embodiment, the floating vacuum head assembly, designated generally by reference numeral 114. includes an outer shell 115 secured to a head flange 116 having a threaded tubular neck 117 at the upper end thereof for threaded engagement with a threaded opening or orifice formed in the air manifold conduit 100. The air passageway formed through the threaded neck 117 communicates with a central bore 118 formed through an internal body 119 flxcd within the upper end of the outer shell 115. A relatively large recess 120 is formed in the lower end of the body 119 in communication with the bore 118, and an annular 5 iron plate 121 is bonded to the bottom of this recess in a position such that the opening therethrough is aligned with the bore 118.

The recess 120 is diametrically dimensioned to accommodate a disk shaped magnet head 122 which is carried at the upper end of a floating sucker tube 123 and which has secured to the upper surface thereof. a small permanent magnet 124. The magnet head 122 seats in a recess formed in the upper end of a tubular sleeve 125 which is slidably mounted in the outer shell 115, and which is limited in its downward movement within the outer shell by a limit pin 126 extended through the outer shell into a slot extending axially in the outer peripheral surface of the shell 115. At its lower end, the floating sucker tube 123, which is slidingly mounted in the tubular sleeve 125, carries a concave suction cup 127 of rubber or other elastomeric material. It will be noted that the axial air passageway through the sucker tube 123 intersects at its upper end, radial air passageways 128 extending to the outer side of the magnet head 122, and that clearance exists between the outer periphery of the magnet head and the recess in which it is seated.

Mounted on one of the vertically extending side plates 14 is a solenoid assembly designated generally by reference numeral 130. The solenoid assembly 130 is secured on that side plate 14 of the printing or duplicating machine which carries certain gears, ratchet and pawl mechanisms which are conventionally employed in the actuation of the feed table 16 for incrementally elevating the feed table so as to maintain a proper level ofthe top of the stack 18 of paper sheets for feeding the duplicator or printing press. This will become better understood as the location and function of the solenoid assembly 130 is further explained.

It will be noted in referring to FIG. 10 that the solenoid assembly includes an elongated. generally rectangular mounting plate 132 which is secured in flatly abutting relation to the outer side of the vertically ex tending side plate 14. A pair of threaded mounting posts 134 are utilized in conjunction with suitable taps 136 for mounting a solenoid housing 138 in spaced relation to the side plate 14. The coil 140 of the solenoid is mounted inside the solenoid housing 138, and a slotted plunger limit plate 142 is secured to the side of the housing 138 and projects downwardly therefrom. The plunger limit plate 142 has a central slot 144 provided therein. as shown in FIG. 10 of the drawings. which slot receives one end of a transverse key 146 carried on the lower end of the solenoid armature plunger 148. Electric current is supplied to the solenoid coil 140 by a lead 150. A bushing 152 secured to the mounting plate 132 is mounted in a hole or opening 153 formed in the side plate 14, and is connected to a female socket 154 exposed on the inner side of the vertically extending plate 14. The solenoid mounting plate 132 is held against the vertically extending side plate 14 by means of a cover plate 156 which covers the opening 153 through the side plate. A pair of threaded screws 158 are projected through the cover plate 156 and into threaded apertures formed in the solenoid mounting plate 132.

A main electrical power supply line 160 is connected through the bushing 152 to the female socket or receptacle 154, and provides electrical power to this socket, as well as to the solenoid coil 140 via the lead 150. An electrical lead 162 extends from the microswitch 76 and the light 80 to a male plug 164 used for connecting the microswitch and light to the source of power through the socket 154. The arrangement of the electrical circuitry which includes the solenoid coil 140, the microswitch 76 and the light 80 can best be perceived by reference to FIG. 11. It will here be noted that the light 80, along with a suitable electrical resistor 166, are provided in parallel with the solenoid 130 and the microswitch 76. The microswitch 76 is shown in its normally open position, in which position sufficient electrical current flows through the resistor I66 and the light 80 to illuminate the light. When the microswitch 76 is closed, the magnitude of resistance offered by the resistor 166 is such that the light 80 will not be illuminated and, of course, at this time, the solenoid coil 140 will be energized.

Referring to FIGS. 12 and 13 of the drawings, illustrated there is a part of the mechanism which is used for arresting and controlling the movements of the feed table 16 as it is normally caused to occur in the type of duplicating machine here under consideration, as well as, in general, many other types of duplicating and printing machines. In machines of this type, a pawl lever 170 is provided as a part of the feed table elevating mechanism. and undergoes an oscillating movement in correspondence to each increment of elevation of the feed table 16. The structure associated with the pawl lever 170 and cooperating therewith in effecting incremental elevation of the feed table is conventional and well understood in the art. There is generally also provided on duplicating machines of the type under description, a pawl latch lever 172 which carries a latching flange 172a.

In the operation of such duplicators as heretofore constructed, the pawl latch lever 172 is periodically caused to become disengaged from the pawl lever 170 by the extension of a spring 174 as regulator plate 176, to which one end of the spring 178 is secured, is caused to move clockwise by the reciprocating movement of the link assembly 180. The timing of the unlatching or disengagement of the pawl latch lever 172 from the pawl lever 170 is controlled by a mechanical sensing system conventionally provided on duplicators and printing machines of the type under discussion. The mechanical sensing system mechanically senses the level of the top side of the paper stack, and when the level drops too low, causes the pawl latch lever 172 to be disengaged from the pawl lever 170 to permit the feed table 16 to be elevated in increments until the mechanical sensing system again senses that the paper stack 18 is of proper height. The mechanical linkage then again enables the pawl latch lever 172 to engage the pawl lever 170, and thus to arrest the continuing vertical movement of the feed table.

As will be perceived in referring to FIGS. 12 and 13, the pawl latch lever 172 pivots on a shaft 182 to which it is keyed by means ofa hub 184. The assembly of the present invention functions to override the normal pivoting movement of the pawl latch lever 172 to retain this lever in engagement with the pawl lever 170 at certain times as controlled by the electro-mechanical sensing system of the invention in the manner hereinafter described. An adapter arm 190 has one of its ends resting upon the key 146 ofthe solenoid assembly 130, and it will be perceived in referring to FIG. 12 that the adapter arm, at this end, is flattened and bent into a plane such that one edge portion of the adapter arm rides upon the upper side of the key 146. At its opposite end, the adapter arm 190 is bent through a circular configuration to provide an eye or hub 194 which can be changed in its diametric dimension by means of a constricting screw 196 extended through a hole provided in one portion of the adapter arm, and through an aligned threaded hole provided in the turned back end portion of the adapter arm. The eye or hub 194 is fitted around the hub 184 of the pawl latch lever I72 and tightly engages the hub of this lever so that the lever cannot be oscillated about its rotational axis without concurrent pivotation of the adapter arm 190. It will be noted in referring to FIGS. 12 and 13 that when the solenoid plunger 148 is fully extended as a result offalling under gravitational influence at a time when the coil 140 of the solenoid is not energized. the adapter arm I occupies the position shown in FIGS. 10 and 13, and in such position, causes the pawl latch lever 172 to be disengaged from the pawl lever 170. When. on the other hand, the coil of the solenoid assembly 130 is enerigzed, at a time hereinafter described, the plunger 148 is retracted upwardly, causing the lower end of the adapter arm to be moved upwardly, and causing the pawl latch lever 172 to pivot into locking engagement with the pawl lever 170. At this time, the feed table 16 is prevented from undergoing further vertical movement to elevate the stack 18 of paper sheets.

OPERATION In the operation of the paper feed regulating assembly of the invention, a stack 18 of sheets of paper, envelopes or other materials to be fed to the printing or duplicating mechanism (not shown) disposed within the frame superstructure 12 is placed on the feed table 16. The exposed surface of the uppermost sheet or envelope is placed beneath the suction cups 112 of the several floating vacuum heads 102 so that the cups bear flatly against the paper or envelope. In machines which have mechanical sensing systems, including feeler fingers 200 of the type herein shown in FIGS. 1 and 2, these feeling fingers are elevated to a level in the mechanism such that the fingers are inoperative to sense the upper side of the stack of papers or envelopes, and elevtion of the feed table is controlled solely by the electro-mechanical regulating assembly of the present invention. It should be pointed out, however, that the air orifices 202 formed in the tubes which support the feeler fingers 200 continue to be points of discharge of air jets which are directed against the sheets at the top side of the stack 18, and thus aid in breaking the adherent forces caused by static electricity between the sheets in the same manner as this airjet system customarily functions.

Before departing from a discussion of the placement of the floating vacuum heads 102 in contact with the surface of the upper sheet of paper in the stack 18, it should be pointed out that a significant advantage is afforded by the types of floating vacuum heads I02 or 114 utilized in the present invention over those which have been heretofore employed in machines of this type. In referring to FIG. 8, it will be noted that the sucker tube 110 is freely reciprocable within the tubular body 106. Thus. where materials to be fed to the press have an uneven transverse thickness, as in the case of envelopes, the distortion or departure from a horizontal plane which characterizes the upper surface of the stack of materials can be accommodated by the vacuum heads. ln other words, a stack of envelopes. for example, stacked upon the feed table 16 will usually extend to a lower level at one side of the upper surface of the stack than at the other side due to the superimposition of the flaps of the envelopes in the stack. There is thus a necessity for the suction cups carried on the vacuum heads at one side of the vacuum head array to be disposed at a lower level, in order to contact the top envelope, than is required of the suction cups on the vacuum heads toward the other side of the envelope stack. The necessity for such differences in the levels of the suction cups 112 can be accommodated by the following action of the sucker tubes 110 they drop by gravity lower within the tubular body 106 until the respec tive suction cup comes in contact with the stack of envelopes. At this time, the flow of air through the suction cup is terminated by sealing of the flexible elastomeric material in the suction head against the surface of the envelope, and the envelope is then pulled upwardly at its low side until a transverse alignment of the envelope in a horizontal plane occurs as all of the suction heads of the several vacuum heads 102 becomes equalized. A slight bleed of air around the flanges 108 and 113 prevents the suction head 112 and its respective sucker tube 110 from being pulled or retracted completely upwardly within the tubular body 106 at this time, and allows relatively friction free upward movement of the sucker tube within the tubular body 106.

In vacuum heads of the type previously in use in which a rigid tubular member incapable of extension or telescoping collapse is used to mount the respective suction cups 112 at a fixed position or level over the stack 18 of papers or envelopes, those suction heads located over the low side of the stack of envelopes frequently would not make contact with the upper surface of the top envelope. resulting in a failure of sufficient vacuum to be developed at the other suction heads to properly and adequately lift and move the envelopes or paper into the printing mechanism. In other words. the failure of some of the suction cups to make contact with the top envelope at the low side of the stack allowed sufficient air to be drawn through these non-contacting suction cups to reduce the vacuum to an ineffective low level at the other vacuum heads, and thereby destroy the efficiency of the pickup and feeding system. and the proper functioning of the suction heads.

in a duplicating system of the type described, the function of the floating vacuum head assemblies 102 or 114 is to grip the envelope or top sheet of paper at its upper surface and then. through rotation of the air manifold conduit 100 about its longitudinal axis and consequent rotation of the floating vacuum head assemblies. to move the top sheet of paper or top envelope into feed rollers to the printing or duplicating mechanism disposed within the frame superstructure.

It has also been characteristic of the types of floating vacuum head assemblies previously provided that the vacuum heads in the array which were not in use as. for example, those vacuum heads disposed outwardly of the stack of sheets of paper where relatively narrow sheets were being passed through the apparatus had to be removed from the air manifold conduit 100 by unscrewing. and then the threaded openings into which the threaded necks of the floating vacuum heads were normally secured were closed or plugged with a suitable threaded plug. Alternatively. the suction cups had to be removed and the ends plugged or capped. This was necessary in order to preserve the integrity of the vacuum system, and to render inoperative those locations in the vacuum head array which were not in use for lifting the particular types of paper sheets or envelopes being fed to the printing mechanism.

The embodiment of the floating vacuum head assembly illustrated in FIG. 9 is specially adapted to obviate the necessity for removing vacuum heads which are not in use due to being disposed outside the projected position of the sheets of paper in the stack 18. Thus, instead of having to remove those vacuum head assemblies 114 not in use from the air manifold conduit 100, and replace them with a plug closing the threaded orifice from which they are removed in the manifold conduit, it is merely necessary, in order to render the floating vacuum head assemblies inoperative, to push upwardly on the tubular sleeve 125 and the floating sucker tube 123 until the permanent magnet 124 is drawn against, and contacts, the iron plate 121. At this time. the central opening through the iron plate 121 will be sealed by the magnet 124, and the bleeding of air through the air passageway in the floating sucker tube 123 will be terminated and no air can be drawn through the thus blocked floating vacuum head assembly into the air manifold conduit 100. It is then a simple matter to later reactivate the floating vacuum head assembly 114 thus temporarily closed by merely pulling down on the tubular sleeve 125 until its downward movement is arrested by contact of the limit pin 126 with the upper end of the axial groove formed in the outer side of the tubular sleeve. At this time, air can flow through the air passageway in the floating sucker tube 123, through the radial air passageways 128 in the magnet head 122 and through the central bore 118 in the internal body 119 so that suction can be applied through the suction cup 127. Moreover, the sliding movement of the tubular sleeve 125 within the outer shell 11S, and of the floating sucker tube 123 within the tubular sleeve allows the position of the suction cup 127 to be adjusted to accommodate the floating vacuum head assembly 114 to various levels occurrent within the upwardly facing surface of the top sheet or envelope. as may be required in order to achieve perfect and smooth feeding of the sheets to the printing mechanism.

In commencing the operation of the paper feed regulating assembly of the invention, the microswitch assembly 72 is manually adjusted in its sensing capability and location to assure that the upper sheet in the stack 18 will always be at the proper level to assure the most efficient feeding. This adjustment of the microswitch assembly 72 is accomplished by first placing the assembly at a selected location over the top sheet or top envelope, etc. in the stack 18 by moving the elongated plate 24 transversely on the slide bar 20c until the microswitch assembly is over a portion of the stack at which the top sheet or envelope undergoes relatively little change in its planar alignment or lateral position as the stack is fed upwardly by upward incremental movement of the feed table 16. This will usually be a position about half way across the transverse dimension of the top sheet or envelope. which position represents a mean vertical level as between two side edges of the stack in those instances where there is any slope. or inclination of the top side of the stack from a horizontal plane.

Next. the adjustable contact screw is manually adjusted as a few sheets of paper are fed slowly into the printing mechanism. This is for the purpose of optimizing the location of the lower end or head of the adjustable contact screw 85 so that the response of the microswitch assembly 70 to the location of the top side of the stack of sheets 18 affords the smoothest and most efficient feeding of the sheets to the printing mechanismv The manner in which this is empirically effected, and in which optimization occurs will be better understood from the subsequent description of the overall operation of the paper feed regulating assembly of the inven tion. and particularly ofthe manner in which the microswitch assembly 70 senses and develops signals indica tive of the times at which the feed table 16 should be incrementally elevated to maintain the top side of the stack 18 at the correct location for trouble free feeding of the sheets to the machine. It may be noted before passing on that after the adjustable contact screw 85 has been set to the desired position, it is retained in this position by the friction finger 92 which prevents rotational movement of the contact screw in the nut 90 under the influence of vibration imparted to the screw during operation of the apparatus.

At the time of adjustment and setting of the microswitch assembly 70, the backstep structures 52 are positioned at the sides and rear edge of the stack 18 in such way that the stack alignment over the feed table 16 is correct and the stack 18 is in the position desired and is vertically true beneath the microswitch assembly 70. [n this regard. the adjustability and ease of use of the backstep structures 52 as hereinbefore described plays an important role, since these structures can be quickly and easily positioned at any desired location, and afford a wide range of selectivity of position due to their reversibility of orientation as depicted in the two positions shown in full and dashed lines in FIG. of the drawings.

With the microswitch assembly 70 thus adjusted in its position, and the backstep structure 52 set to maintain the paper stack 18 in the desired position and correct alignment, operation ofthe duplicator or printing press is commenced. As previously pointed out. the status of the microswitch 76 is normally open. lts closure is effected by the upward movement of the spring plate 88, and upward movement of the spring plate is in turn effected by upward movement of the adjustable contact screw 85 as brought about by the upward movement of the paper stack 18. Assuming initially that feeding of the paper is commenced at a time when the microswitch assembly 70 has been adjusted so that the top of the stack 18 of paper sheets is high enough to bias the adjustable contact screw upwardly. so that the spring plate 88 closes the microswitch 76, at this time. the circuit to the solenoid assembly 130 is closed. and the coil 140 ofthe solenoid is energized. This results in the solenoid plunger 148 being retracted into the coil. Upward movement of the plunger 148 causes upward movement of that end of the adapter arm 190 which is in contact with the transverse key [46. The adapter arm 190 is thus pivoted about the axis of the shaft 182 and the frictional engagement ofthe hub 194 of the adapter arm with the hub 184 ofthe pawl latch lever 172 causes the pawl latch lever to pivot or oscillate in a counterclockwise direction to bring its latching flange 1720 into engagement with the pawl lever 170. The pawl lever 170 is thus locked against oscillation at this time, and this locking engagement prevents the mechanism provided on the duplicator or printer press for elevating the feed table 16 from being operative. In sum, at

14 the outset of the paper feeding operation with the status in effect which has been described that is. the top of the stack [8 being at a level such that the adjustable contact screw is elevated sufficiently to close the microswitch 76 the paper feed table is rendered operative and does not move upwardly.

The top sheets of paper are then fed by the pivoting vacuum head assembly 102 through advancing rollers into the printing or duplicating mechanism in a manner which is conventional in the art. This procedure is aided by the air jets delivered from the orifices 202 in tubes leading to the conventional mechanical feelers 200 which are, at this time, set so that they do not function to actuate or energize the feed table operating mechanism of the apparatus. After a sufficient number of the sheets or envelopes have been fed to the printing or duplicating structure to lower the top of the stack 18 to a point where the adjustable contact screw 85 has moved downwardly by a significant increment, the spring plate 88 is concurrently moved downwardly, thereby permitting the microswitch 76 to return to its normally open position.

When this occurs. the electric circuit to the solenoid coil [40 is opened. and the solenoid is deeneregized. This permits the plunger [48 to fall downwardly by gravity until the transverse key 146 is arrested in its downward movement by the lower end of the slot 144 formed in the plunger limit plate 142. This downward movement of the plunger 148 and the transverse key 146 allows the adapter arm to pivot downwardly. and effects the release of the pawl latch lever 172 from the pawl lever 170. The conventional mechanism provided for incrementally elevating the feed table 16 is now free to operate. and the feed table will be moved upwardly in increments as may be necessary to restore the upper level of the stack of paper sheets 18 to a position where the microswitch 76 isagain closed to arrest upward movement of the feed table in the manner previously described. Thus. as the feed table 16 continues to move upwardly, the top of the stack 18 of paper sheets moves upwardly until it bears against the lower side of the adjustable contact screw 85. Continued upward movement of the paper stack biases the spring plate 88 upwardly until the microswitch 76 is closed.

In this regard, it should be pointed out that an important feature of the present invention is the ability of the spring plate 88, due to its length and its flexibility. to override the position of closure of the microswitch 76, and in this way accommodate the completion of one increment of movement of the feed table l6. In other words, the mechanism which elevates the feed table 16, as it is conventionally provided on most duplicators and printing machines. effects such elevation through a ratchet and pawl stepping mechanism in which the stroke of an oscillating dog or pawl device. in conjunction with a ratchet. effects one increment of vertical movement of the feed table which is correlated to one stroke of the pawl while in engagement with the tooth of the ratchet. To allow this one stroke to be completed without physical damage to the microswitch assembly 70, the spring plate 88 can continue to yield in an upward direction even after the microswitch 76 has been closed. and thus permit the incremental movement of the feed table 16 to be completed. This aspect of the construction of the microswitch assembly 70 has the further advantage of reducing the frequency of ON- OFF operation of the microswitch 76 and operation of the feed table 16 so that starting and stopping of these mechanisms does not occur so frequently. since several more sheets must be fed to the printing or duplicating mechanism before the distorted spring plate 88 will move downwardly a sufficient distance to permit the microswitch 76 to be opened.

The electro-mechanical feed regulating assembly of the present invention offers a number of marked advantages over mechanical sensing systems of the type previously in use. Thus. the feeler fingers 200 used in such mechanical sensing systems are frequently placed at the leading or feed side of the stack 18 of paper sheets and function by hearing down on the upper side of the paper stack. The fingers follow the upper side of the stack until the fingers have dropped to a level such that a responsive mechanism detects this lower limit of travel of the fingers. and actuates the feed table elevating mechanism. The touch" or feel of such mechanical fingers is frequently too heavy or insensitive, and the fingers do not function to accurately sense highly compressible papers or envelopes or materials which can be pushed downwardly from their normal position as a result of the expression of air from between the sheets. or compression of the stack itself. This insensitivity results. frequently, in the top papers in the stack being pushed downwardly against the underlying papers by compression to such an extent that the sheets bind against each other and will not feed freely.

Further. it will be noted that the normal position of the mechanical sensing fingers 200 in the conventional mechanism is disposed at the leading side of the stack 18 of paper sheets. and that in this position the fingers tend to compress or push the sheets downwardly against each other so as to prevent the free flow of air from the jets 202 between top sheets. Interference is thus afforded with the normal function of the air jets in breaking the static electricity bond established between these sheets. and the air does not effectively separate the sheets as intended. With the arrangement of the present invention in which the microswitch assembly 70 is disposed at. and functions upon. the opposite (trailing) side of the stack 18, air from the jets 202 is free to pass between the leading edges of the top sheets of paper. and to separate these sheets effectively.

in general. the very sensitive response of the spring plate 88 to very slight upward pressure on the adjustable contact screw 85 will result in closure of the microswitch 76 to stop further upward movement of the feed table 16, thus avoiding compression of the sheets or envelopes within the stack. The frictional adherence between adjacent sheets or envelopes is thus minimized. and free feeding to the printing and duplicating mechanisms continues without interruption or malfunction. Further. the adjustability of the adjustable contact screw 85 permits the microswitch assembly 70 of the present invention to be customized in its setting and sensitivity to any particular stock which is to be fed to the machine. A very slight adjustment may be made for different weights or finishes of paper which characterize the paper in the stack l8, and the same is true of such variations in stock as the feeding of envelopes or other similar materials.

It will be perceived in referring to the drawings and to the foregoing discussion that the microswitch assembly 70 is disposed in a position such that a sliding adjustment of the assembly can render it inoperative and deactivate the electro-mechanical feeding system of the present invention. and permit the mechanical feeler fingers 200 to be moved down to assume their normal function as such machines are manufactured. in other words, installation of the microswitch assembly of the present invention does not require removal of the normal mechanical sensing system which is conventionally provided. and this system remains available should it be desirable in any instance to use it. Further. the location at which the microswitch assembly is mounted when in use does not interfere with the air jets normally provided in close proximity to the mechanical feeler fingers 200 as hereinbefore described. it is also to be noted that at such time as the microswitch 76 is open. and the normal paper feeding function of the feed table 16 is occurring. the light 80 is illuminated due to the flow of sufficient current through the parallel circuit which contains it at this time. An operator is thus apprised by the ON-OFF status of the light 80, which is visible through the light aperture 74 in the hollow housing 72, of the proper functioning of the paper feed regulating assembly of the present invention.

Although certain preferred embodiments of the invention have been herein described and are illustrated in the drawings. it will be understood that various changes in the illustrated and described structure, and in the overall combination can be effected without departure from the basic principles underlying the invention. Changes and innovations of this type are therefore deemed to be circumscribed by the spirit and scope of the invention. except as the same may be necessarily limited by the appended claims. or reasonable equivalents thereof.

What is claimed is:

1. An assembly for regulating the feeding of paper to a copying machine comprising:

a paper feed table;

means for elevating the paper feed table;

a microswitch assembly spaced vertically from, and

disposed over. the paper feed table, said microswitch assembly comprising: housing means;

a microswitch mounted in the housing means and including a downwardly facing switch contact vertically movable to open and close the microswitch;

a spring plate mounted as a cantilever in said housing means and extending across and touching at a point intermediate its length. said switch contact for moving the switch contact from a normally open to a closed position when said spring plate is pushed vertically upwardly against said switch contact;

an adjustable contact screw extending in a vertical direction through. and adjustably secured to. a free end of the cantilevered spring plate. and positioned for contact by the uppermost sheet of paper in a stack of paper carried on said feed table, said contact screw being adjustable in the extent to which it extends downwardly from said spring plate;

a solenoid connected to said microswitch for actuation when said microswitch is closed; and mechanical linkage connected between said solenoid and said means for elevating the feed table for inactivating said elevating means when the status of energization of said solenoid is changed.

2. An assembly for regulating the feeding of paper to a copying machine as defined in claim 1 wherein said means for elevating the paper feed table comprises:

an oscillating pawl lever;

means connected to said pawl lever and undergoing movement when said pawl lever is oscillated to elevate said feed table; and

a pawl latch lever pivotally supported for engaging said pawl lever in one position to prevent said pawl lever from oscillating, and for disengaging said pawl lever in a second position to allow said pawl lever to oscillate; and

wherein said mechanical linkage includes an adaptor arm having one end connected to said pawl latch lever, and a second end connected to said solenoid for pivoting said pawl latch lever to said one position when said solenoid is energized, and to said second position when said solenoid is de-energized.

3. An assembly for regulating the feeding of paper to a copying machine as defined in claim 1 wherein said microswitch is connected in series with said solenoid, and said assembly is further characterized as including a light connected in parallel with said microswitch and said solenoid whereby said light is illuminated when said microswitch is open and said solenoid is de-energized.

4. An assembly for regulating the feeding of paper to a copying machine as defined in claim 1 wherein said assembly further includes:

a horizontally extending, elongated slide bar positioned at a level spaced upwardly from the feed table; a clamp structure movably mounted on the slide bar for axial movement therealong; a horizontally projecting elongated plate slidingly extended through the clamp structure in a direction normal to said slide bar. and frictionally engaged by said clamp structure; and backstep means pivotally mounted on an end portion of said elongated plate and pivotable through 180 on said elongated plate, said backstep means comprising: an L-shaped supporting plate having a horizontal upper leg and a downwardly extending leg; and

means resiliently retaining said horizontal leg in a selected one ofa plurality of positions in juxtaposition to said elongated plate.

5. An assembly for regulating the feeding of paper to a copying macchine as defined in claim 1 wherein said assembly further includes:

a horizontally extending, elongated slide bar extending in a direction transversely of the paper feed table at a location spaced upwardly from the feed table;

a clamp structure slidingly mounted on the slide bar for sliding movement in an axial direction therealong;

an elongated plate slidingly extended through the clamp structure in a direction normal to said slide bar and frictionally engaged by said clamp structure, said elongated plate having said housing means detachably mounted at one end thereof disposed over said paper feed table.

6. An assembly for regulating the feeding of paper to a copying machine as defined in claim I and further characterized as including:

a plurality of floating vacuum heads positioned over said feed table at a level to engage the upper side of a stack of paper sheets carried on said feed table at a time when the uppermost sheet in said stack is in contact with said contact screw. each of said floating vacuum heads comprising:

a vertically extending tubular body having an upper end and a lower end;

a sucker tube slidingly disposed in said tubular body for vertical movement therein, and having a portion projecting from the lower end of said tubular body; and

a flexible, elastomeric suction cup attached to the lower end of said sucker tube for engaging, by suction, the uppermost of said top sheets of paper in said stack;

an elongated, horizontally extending air manifold conduit connected at spaced intervals therealong to the upper ends of said tubular bodies; and

means for oscillating said manifold conduit periodically to displace the uppermost of said paper items into said copying machine as said vacuum heads are oscillated with said manifold conduit.

7. An assembly for regulating the feeding of paper as defined in claim 1 wherein said housing means includes:

a hollow housing having an upper side and a lower side and having the microswitch mounted therein, said housing having a light aperture in the upper side thereof;

a light mounted in said housing adjacent said light apcrture;

electrical circuitry connected to said microswitch and light for illuminating the light when said microswitch is open; and

a closure plate closing the lower side of the housing and having said spring plate secured to the upper side thereof, said closure plate having an opening therein to pass a downwardly extending portion of said contact screw.

8. An assembly for regulating the feeding of paper as defined in claim 1 wherein said solenoid is mounted to allow the armature plunger thereof to gravitate downwardly when the coil of the solenoid is de-energized, and wherein said mechanical linkage includes an adapter arm having an end positioned to gravitate downwardly when said solenoid armature gravitates downwardly in the de-energized status of the coil of the solenoid, and to be pulled upwardly when said solenoid plunger is retracted in an upward direction by energization of the coil of the solenoid.

9. An assembly for regulating the feeding of paper to a copying machine as defined in claim 2 wherein said solenoid comprises:

a coil;

an armature plunger disposed adjacent said coil in a position to reciprocate vertically upon energization and de-energization of said coil;

a transverse key secured to said plunger and projecting normal to the direction of reciprocating movement of said plunger, said key supporting said one of said adapter arm;

a solenoid housing containing said coil;

a plunger limit plate secured to said housing and projecting downwardly therefrom. said housing having a vertically extending slot therein receiving said key for limiting the downward movement of said plunger; and

a mounting plate connected to said solenoid housing and adapted for securement to said copying machine.

10. An assembly for regulating the feeding of paper to a copying machine as defined in claim 2 wherein said microswitch is connected in series with said solenoid.

19 and said assembly is further characterized as including a light connected in parallel with said microswitch and said solenoid whereby said light is illuminated when said microswitch is open and said solenoid is de-energized.

11. An assembly for regulating the feeding of paper to a copying machine as defined in claim 2 and further characterized including means movably supporting said microswitch assembly for selective sliding rnvoement thereof in two directions each extending normal to the vertical direction of elevation of said paper feed table whereby said microswitch assembly can be selectively positioned relative to a stack of paper items carried on said paper feed table, said means movably sup porting said microswitch assembly being adapted for mounting on said copying machine.

12. An assembly for regulating the feeding of paper to a copying machine as defined in claim 2 and further characterized as including air jet means spaced horizontally from said microswitch assembly and positioned over said feed table for directing air between sheets of paper in a stack of paper sheets carried on said feed table.

13. An assembly for regulating the feeding of paper to a copying machine as defined in claim 2 wherein said assembly further includes:

a horizontally extending, elongated slide bar positioned at a level spaced upwardly from the feed table;

a clamp structure movably mounted on the slide bar for axial movement therealong;

a horizontally projecting elongated plate slidingly extended through the clamp structure in a direction normal to said slide bar. and frictionally engaged by said clamp structure; and

backstep means pivotally mounted on an end portion of said elongated plate and pivotable through 180 on said elongated plate. said backstep means comprising: an L-shaped supporting plate having a horizontal upper leg and a downwardly extending leg; and

means resilientlly retaining said horizontal leg in a selected one ofa plurality of positions in juxtaposition to said elongated plate.

14. An assembly for regulating the feeding of paper to a copying machine as defined in claim 2 and further characterized as including:

a plurality of floating vacuum heads positioned over said feed table at a level to engage the upper side of a stack of paper sheets carried on said feed table at a time when the uppermost sheet in said stack is in contact with said contact screw. each of said floating vacuum heads comprising:

a vertically extending tubular body having an upper end and a lower end;

a sucker tube slidingly disposed in said tubular body for vertical movement therein. and having a portion projecting from the lower end of said tubular body; and

a flexible. elastomeric suction cup attached to the lower end of said sucker tube for engaging. by suction, the uppermost of said top sheets of paper in said stack;

an elongated. horizontally extending air manifold conduit connected at spaced intervals therealong to the upper ends of said tubular bodies; and

means for oscillating said manifold conduit periodi eally to displace the uppermost of said paper items into said copying machine as said vacuum heads are oscillated with said manifold conduit. 15. An assembly for regulating the feeding of paper to a copying machine as defined in claim 2 wherein said 5 housing means includes:

a hollow housing having an upper side and a lower side and having the microswitch mounted therein. said housing having a light aperture in the upper side thereof;

a light mounted in said housing adjacent said light aperture;

electrical circuitry connected to said microswitch and light for illuminating the light when said microswitch is open; and

a closure plate closing the lower side of the housing and having said spring plate secured to the upper side thereof, said closure plate having an opening therein to pass a downsardly extending portion of said contact screw.

16. An assembly for regulating the feeding of paper to a copying machine as defined in claim 2 wherein said solenoid is mounted to allow the armature plunger thereof to gravitate downwardly when the coil of the solenoid is de-energized. and wherein said mechanical linkage includes an adapter arm having an end positioned to gravitate downwardly when said solenoid armature gravitates downwardly in the de-energized status of the coil of the solenoid, and to be pulled upwardly when said solenoid plunger is retracted in an upward direction by energization of the coil of the solenoid.

17. An assembly for regulating the feeding of paper to a copying machine as defined in claim 4 wherein said horizontally projecting, elongated plate has a pair of horizontally spaced protuberances on one side thereof,

and said horizontal leg has a pair of spaced apertures therein adapted to detachably engage said protuberances in two different positions of said horizontal leg.

18. An assembly for regulating the feeding of paper to a copying machine as defined in claim 17 wherein said means resiliently retaining said horizontal leg in a selected one of a plurality of positions comprises:

a bolt having an end secured to said horizontally projecting elongated plate at a location between said protuberances and projecting downwardly through an opening in said horizontal leg to a bolt head spaced from said horizontal leg; and

a helical compression spring around said bolt between the bolt head and horizontal leg.

19. An assembly for regulating the feeding of paper to a copying machine as defined in claim 1 and further characterized as including means for directing air against the upper end portion of a stack of paper sheets 55 stacked on said feed table for preventing the uppermost sheets in the stack from adhering to each other.

20. In a duplicating machine having a paper feed table. means for elevating the paper feed table and a stack of paper sheets carried thereon. and means for 60 periodically. and in sequence. feeding paper sheets from the top of the stack into duplicating structure of the machine adapted to form indicia on the sheets, the improvement which comprises:

a horizontally extending. elongated slide bar extending transversely across the machine at a level spaced upwardly from the feed table;

a clamp structure slidingly mounted on the slide bar for sliding movement therealong:

2 l a horizontally extending. elongated plate slidingly extended through the clamp structure in a direction normal to said slide bar and frictionally engaged by said clamp structure; and backstep means pivotally mounted on an end portion of said elongated plate and pivotable through 180 on said elongated plate. said backstep means com prising: an L-shaped supporting plate having a horizontally extending upper leg and a downwardly extending lower leg; and

means resiliently retaining said horizontal leg in a selected one of a plurality of positions in juxtaposition to said elongated plate.

21. The improvement defined in claim wherein said backstep means is further characterized in including an arcuate pressure plate extending in an are between the lower end of said downwardly extending lower leg and said upper leg.

22. The improvement defined in claim 20 wherein said means resiliently retaining said horizontal leg in a selected one of a plurality of positions comprises:

a bolt having an end secured to said horizontally projecting. elongated plate and projecting downwardly through an opening in said horizontal leg to a bolt head spaced from said horizontal leg; and

spring means between the bolt head and the horizontal leg resiliently urging the horizontal leg against said horizontally projecting, elongated plate.

23. The improvement defined in claim 20 and further characterized in including a pair of horizontally spaced protuberances on said horizontally extending. elongated plate engaging mating apertures in the horizontally extending upper leg of said backstep means.

24. The improvement defined in claim 22 and further characterized as including:

a pair of spaced. downwardly projecting hemmispherical protuberances secured to said horizontally projecting, elongated plate at equal distances from. and on opposite sides of. the point of securement of said bolt to said elongated plate; and

means in said horizontally extending upper leg detachably engaging said protuberances.

25. The improvement defined in claim 24 wherein said horizontally extending upper leg has a transverse width substantially equal to the distance between said protuberances, and said bolt opening in said upper leg is located at the midpoint of said transverse width.

26. The improvement defined in claim 22 wherein said backstep means is further characterized in including an arcuate pressure plate extending in an are between the lower end of said downwardly extending lower leg and said upper leg.

27. An assembly for feeding paper stock to a duplicating machine comprising:

a paper feed table:

means for elevating the paper feed table;

a sensing device disposed above the paper feed table for sensing the height ofa stack of paper items carried on said paper feed table by contact with the uppermost said paper items;

means connected to said table elevating means and responsive to said sensing means for controlling the actuation of said table elevating means in correspondence to the sensed height of said stack of paper items;

a plurality of floating vacuum heads positioned over said feed table at a level to engage the uppermost paper item in said stack at a time when the uppermost paper item is sensed by said sensing device.

each of said vacuum heads comprising;

a vertically extending tubular body having an upper end and a lower end;

a sucker tube reciprocably telescoped in said tubular body and having a portion projecting from the lower end of said tubular body;

a flexible. elastomeric suction cup attached to the lower end of said sucker tube for engaging, by suction. the uppermost of said paper items; and

magnetic engaging means in said tubular body for preventing reciprocation of said sucker tube in said tubular body when said sucker tube is positioned at a selected location in said tubular body;

an elongated. horizontally extending air manifold conduit connected at spaced intervals therealong to the upper ends of said tubular bodie means for oscillating said manifold conduit periodically to displace the uppermost of said paper items into said duplicating machine as said vacuum heads are oscillated with said manifold conduit.

28. An assembly for feeding paper stock to a duplicating machine comprising:

a paper feed table:

means for elevating the paper feed table;

a sensing device disposed above the paper feed table for sensing the height of the stack of paper items carried on said paper feed table by contact with the uppermost of said paper items. said sensing device comprising:

a microswiteh assembly including;

a microswiteh; and

an adjustable screw having a part constituting the lowermost portion of the microswiteh assembly. and being manually adjustable in its vertical position to facilitate selection of the height of such stack at which the microswiteh will be closed when the stack of paper items exceeds said selected height;

means connected to said table elevating means and responsive to said sensing means for controlling the actuation of said table elevating means in correspondence to the sensed height of said stack of paper items;

a plurality of floating vacuum heads positioned over said feed table at a level to engage the uppermost paper item in said stack at a time when the uppermost paper item is sensed by said sensing device. each of said floating vacuum heads comprising;

a vertically extending tubular body having an upper end and a lower end;

a sucker tube reciprocably telescoped in said tubular body and having a portion projecting from the lower end of said tubular body; and

a flexible. elastomeric suction cup attached to the lower end of said sucker tube for engaging, by suction. the uppermost of said paper items;

an elongated. horizontally extending air manifold conduit connected at spaced intervals therealong to the upper ends of said tubular bodies; and

means for oscillating said manifold conduit periodically to displace the uppermost of said paper items into said duplicating machine as said vacuum heads are oscillated with said manifold conduit.

29. An assembly for regulating the feeding of paper to a copying machine comprising:

a paper feed table;

means for elevating the paper feed table;

a microswitch assembly spaced vertically from, and

disposed over, the paper feed table, said microswitch assembly comprising; housing means;

a microswitch mounted in the housing means and including a downwardly facing switch contact vertically movable to open and close the microswitch;

a spring plate mounted as a cantilever in said housing means, and extending across and touching at a point intermediate its length, said switch contact, for moving the switch contact from a normally open to a closed position when said spring plate is pushed vertically upwardly against said switch contact; and

manually adjustable microswitch closing means operatively associated with said microswitch and spring plate in said microswitch assembly for manually selectively adjusting the closure of said microswitch in correlation to the height of a stack of papers on said feed table, said microswitch closing means including contact means projecting downwardly below said spring plate for contact by the uppermost sheet of paper in a stack of paper carried on said feed table;

a solenoid connected to said microswitch for actuation when said microswitch is closed; and

a mechanical linkage connected between said solenoid and said means for elevating the feed table for inactivating said elevating means when the status of energization of said solenoid is changed.

30. An assembly for regulating the feeding of paper to a copying machine as defined in claim 29 wherein said microswitch is connected in series with said solenoid. and said assembly is further characterized as including a light connected in parallel with said microswitch and said solenoid whereby said light is illuminated when said microswitch is open and said solenoid is de-energized.

31. An assembly for regulating the feeding of paper to a copying machine as defined in claim 29 wherein said assembly further includes;

a horizontally extending. elongated slide bar extending in a direction transversely of the paper feed table at a location spaced upwardly from the feed table;

a clamp structure slidingly mounted on the slide bar for sliding movement in an axial direction therealong; and

an elongated plate slidingly extended through the clamp structure in a direction normal to said slide bar and frictionally engaged by said clamp structure, said elongated plate having said housing means detachably mounted at one end thereof disposed over said paper feed table.

32. An assembly for regulating the feeding of paper as defined in claim 31 wherein said housing means includes:

a hollow housing having an upper side and a lower side and having the microswitch mounted therein. said housing having a light aperture in the upper side thereof;

a light mounted on said housing adjacent said light aperture;

electrical circuitry connected to said microswitch and light for illuminating the light when said microswitch is open; and

a closure plate closing the lower side of the housing to a copying machine as defined in claim 29 wherein said means for elevating the paper feed table comprises;

an oscillating pawl lever;

means connected to said pawl lever and undergoing movement when said pawl lever is oscillated to elevate said feed table;

a pawl latch lever pivotally supported for engaging said pawl lever in one position to prevent said pawl lever from oscillating, and for disengaging said pawl lever in a second position to allow said pawl lever to oscillate; and

wherein said mechanical linkage includes an adaptor arm having one end connected to said pawl latch lever, and a second end connected to said solenoid for pivoting said pawl latch lever to said one position when said solenoid is energized. and to said second position when said solenoid is de-energized;

34. An assembly for regulating the feeding of paper to a copying machine as defined in claim 29 wherein said solenoid comprises;

a coil;

an armature plunger disposed adjacent said coil in a position to reciprocate vertically upon energization and de-energization of said coil;

a transverse key secured to said plunger and projecting normal to the direction of reciprocating movement of said plunger. said key supporting said one end of said adapter arm;

a solenoid housing containing said coil;

a plunger limit plate secured to said housing and projecting downwardly therefrom, said housing and projecting downwardly therefrom. said housing having a vertically extending slot therein receiving said key for limiting the downward movement of said plunger; and

a mounting plate connected to said solenoid housing and adapted for securement to said copying machine.

35. An assembly for regulating the feeding of paper to a copying machine comprising:

a paper feed table;

means for elevating the paper feed table;

a microswitch assembly spaced vertically from, and

disposed over. the paper feed table. said microswitch assembly comprising;

a housing:

a microswitch in said housing;

manually adjustable switch closing means selectively adjustable to correlate closing of said microswitch with the height of papers in a stack on said feed table;

means movably supporting said microswitch assembly for selective sliding movement thereof in two directions each extending normal to the vertical direction of elevation of said paper feed table whereby said microswitch assembly can be selectively positioned whereby said microswitch assembly can be selectively positioned relative to a stack of paper items carried on said paper feed table. said movable supporting means comprising;

25 26 a horizontally extending. elongated slide bar exan elongated plate slidingly extended through the tending in a direction transversely of the paper clamp structure in a direction normal to said feed table at a location spaced upwardly from the slide bar and frictionally engaged by said clamp feed table; 5 structure, said elongated plate having said housa clamp structure slidingly mounted on the slide ing detachably mounted at one end thereof and bar for sliding movement in an axial direction disposed over said paper feed table. thcrealong;

" UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. q 21 91 Dated November 25, 1975 Inventor(s) Jay E. Stanfield It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 10, line 46, change "elevtion" to -elevation*.

jolumn 11, line 23, change "becomes" to become.

lolumn 14, lines 5 and 6, change "operative" to inoperative-.

Column 24, Claim 35, lines 65 and 66, delete "whereby said microswitch assembly can be selectively positioned" (repeated phrase).

Signed and Scaled this second Day Of March 1976 [SEAL] Arrest:

RUTl-I C. MAISON C. MARSHALL DANN Arresting Officer Commissioner ufParenrs and Trademarks 

1. An assembly for regulating the feeding of paper to a copying machine comprising: a paper feed table; means for elevating the paper feed table; a microswitch assembly spaced vertically from, and disposed over, the paper feed table, said microswitch assembly comprising: housing means; a microswitch mounted in the housing means and including a downwardly facing switch contact vertically movable to open and close the microswitch; a spring plate mounted as a cantilever in said housing means and extending across and touching at a point intermediate its length, said switch contact for moving the switch contact from a normally open to a closed position when said spring plate is pushed vertically upwardly against said switch contact; an adjustable contact screw extending in a vertical direction through, and adjustably secured to, a free end of the cantilevered spring plate, and positioned for contact by the uppermost sheet of paper in a stack of paper carried on said feed table, said contact screw being adjustable in the extent to which it extends downwardly from said spring plate; a solenoid connected to said microswitch for actuation when said microswitch is closed; and a mechanical linkage connected between said solenoid and said means for elevating the feed table for inactivating said elevating means when the status of energization of said solenoid is changed.
 2. An assembly for regulating the feeding of paper to a copying machine as defined in claim 1 wherein said means for elevating the paper feed table comprises: an oscillating pawl lever; means connected to said pawl lever and undergoing movement when said pawl lever is oscillated to elevate said feed table; and a pawl latch lever pivotally supported for engaging said pawl lever in one position to prevent said pawl lever from oscillating, and for disengaging said pawl lever in a second position to allow said pawl lever to oscillate; and wherein said mechanical linkage includes an adaptor arm having one end connected to said pawl latch lever, and a second end connected to said solenoid for pivoting said pawl latch lever to said one position when said solenoid is energized, and to said second position when said solenoid is de-energized.
 3. An assembly for regulating the feeding of paper to a copying machine as defined in claim 1 wherein said microswitch is connected in series with said solenoid, and said assembly is further characterized as including a light connected in parallel with said microswitch and said solenoid whereby said light is illuminated when said microswitch is open and said solenoid is de-energized.
 4. An assembly for regulating the feeding of paper to a copying machine as defined in claim 1 wherein said assembly further includes: a horizontally extending, elongated slide bar positioned at a level spaced upwardly from the feed table; a clamp structure movably mounted on the slide bar for axial movement therealong; a horizontally projecting elongated plate slidingly extended through the clamp structure in a direction normal to said slide bar, and frictionally engaged by said clamp structure; and backstep means pivotally mounted on an end portion of said elongated plate and pivotable through 180* on said elongated plate, said backstep means comprising: an L-shaped supporting plate having a horizontal uppEr leg and a downwardly extending leg; and means resiliently retaining said horizontal leg in a selected one of a plurality of positions in juxtaposition to said elongated plate.
 5. An assembly for regulating the feeding of paper to a copying macchine as defined in claim 1 wherein said assembly further includes: a horizontally extending, elongated slide bar extending in a direction transversely of the paper feed table at a location spaced upwardly from the feed table; a clamp structure slidingly mounted on the slide bar for sliding movement in an axial direction therealong; an elongated plate slidingly extended through the clamp structure in a direction normal to said slide bar and frictionally engaged by said clamp structure, said elongated plate having said housing means detachably mounted at one end thereof disposed over said paper feed table.
 6. An assembly for regulating the feeding of paper to a copying machine as defined in claim 1 and further characterized as including: a plurality of floating vacuum heads positioned over said feed table at a level to engage the upper side of a stack of paper sheets carried on said feed table at a time when the uppermost sheet in said stack is in contact with said contact screw, each of said floating vacuum heads comprising: a vertically extending tubular body having an upper end and a lower end; a sucker tube slidingly disposed in said tubular body for vertical movement therein, and having a portion projecting from the lower end of said tubular body; and a flexible, elastomeric suction cup attached to the lower end of said sucker tube for engaging, by suction, the uppermost of said top sheets of paper in said stack; an elongated, horizontally extending air manifold conduit connected at spaced intervals therealong to the upper ends of said tubular bodies; and means for oscillating said manifold conduit periodically to displace the uppermost of said paper items into said copying machine as said vacuum heads are oscillated with said manifold conduit.
 7. An assembly for regulating the feeding of paper as defined in claim 1 wherein said housing means includes: a hollow housing having an upper side and a lower side and having the microswitch mounted therein, said housing having a light aperture in the upper side thereof; a light mounted in said housing adjacent said light aperture; electrical circuitry connected to said microswitch and light for illuminating the light when said microswitch is open; and a closure plate closing the lower side of the housing and having said spring plate secured to the upper side thereof, said closure plate having an opening therein to pass a downwardly extending portion of said contact screw.
 8. An assembly for regulating the feeding of paper as defined in claim 1 wherein said solenoid is mounted to allow the armature plunger thereof to gravitate downwardly when the coil of the solenoid is de-energized, and wherein said mechanical linkage includes an adapter arm having an end positioned to gravitate downwardly when said solenoid armature gravitates downwardly in the de-energized status of the coil of the solenoid, and to be pulled upwardly when said solenoid plunger is retracted in an upward direction by energization of the coil of the solenoid.
 9. An assembly for regulating the feeding of paper to a copying machine as defined in claim 2 wherein said solenoid comprises: a coil; an armature plunger disposed adjacent said coil in a position to reciprocate vertically upon energization and de-energization of said coil; a transverse key secured to said plunger and projecting normal to the direction of reciprocating movement of said plunger, said key supporting said one of said adapter arm; a solenoid housing containing said coil; a plunger limit plate secured to said housing and projecting downwardly therefrom, said housing having a vertically extending slot therein receiving said key for limiting The downward movement of said plunger; and a mounting plate connected to said solenoid housing and adapted for securement to said copying machine.
 10. An assembly for regulating the feeding of paper to a copying machine as defined in claim 2 wherein said microswitch is connected in series with said solenoid, and said assembly is further characterized as including a light connected in parallel with said microswitch and said solenoid whereby said light is illuminated when said microswitch is open and said solenoid is de-energized.
 11. An assembly for regulating the feeding of paper to a copying machine as defined in claim 2 and further characterized as including means movably supporting said microswitch assembly for selective sliding mvoement thereof in two directions each extending normal to the vertical direction of elevation of said paper feed table whereby said microswitch assembly can be selectively positioned relative to a stack of paper items carried on said paper feed table, said means movably supporting said microswitch assembly being adapted for mounting on said copying machine.
 12. An assembly for regulating the feeding of paper to a copying machine as defined in claim 2 and further characterized as including air jet means spaced horizontally from said microswitch assembly and positioned over said feed table for directing air between sheets of paper in a stack of paper sheets carried on said feed table.
 13. An assembly for regulating the feeding of paper to a copying machine as defined in claim 2 wherein said assembly further includes: a horizontally extending, elongated slide bar positioned at a level spaced upwardly from the feed table; a clamp structure movably mounted on the slide bar for axial movement therealong; a horizontally projecting elongated plate slidingly extended through the clamp structure in a direction normal to said slide bar, and frictionally engaged by said clamp structure; and backstep means pivotally mounted on an end portion of said elongated plate and pivotable through 180* on said elongated plate, said backstep means comprising: an L-shaped supporting plate having a horizontal upper leg and a downwardly extending leg; and means resilientlly retaining said horizontal leg in a selected one of a plurality of positions in juxtaposition to said elongated plate.
 14. An assembly for regulating the feeding of paper to a copying machine as defined in claim 2 and further characterized as including: a plurality of floating vacuum heads positioned over said feed table at a level to engage the upper side of a stack of paper sheets carried on said feed table at a time when the uppermost sheet in said stack is in contact with said contact screw, each of said floating vacuum heads comprising: a vertically extending tubular body having an upper end and a lower end; a sucker tube slidingly disposed in said tubular body for vertical movement therein, and having a portion projecting from the lower end of said tubular body; and a flexible, elastomeric suction cup attached to the lower end of said sucker tube for engaging, by suction, the uppermost of said top sheets of paper in said stack; an elongated, horizontally extending air manifold conduit connected at spaced intervals therealong to the upper ends of said tubular bodies; and means for oscillating said manifold conduit periodically to displace the uppermost of said paper items into said copying machine as said vacuum heads are oscillated with said manifold conduit.
 15. An assembly for regulating the feeding of paper to a copying machine as defined in claim 2 wherein said housing means includes: a hollow housing having an upper side and a lower side and having the microswitch mounted therein, said housing having a light aperture in the upper side thereof; a light mounted in said housing adjacent said light aperture; electrical circuitry connected to said microswitch and light for illuminatIng the light when said microswitch is open; and a closure plate closing the lower side of the housing and having said spring plate secured to the upper side thereof, said closure plate having an opening therein to pass a downsardly extending portion of said contact screw.
 16. An assembly for regulating the feeding of paper to a copying machine as defined in claim 2 wherein said solenoid is mounted to allow the armature plunger thereof to gravitate downwardly when the coil of the solenoid is de-energized, and wherein said mechanical linkage includes an adapter arm having an end positioned to gravitate downwardly when said solenoid armature gravitates downwardly in the de-energized status of the coil of the solenoid, and to be pulled upwardly when said solenoid plunger is retracted in an upward direction by energization of the coil of the solenoid.
 17. An assembly for regulating the feeding of paper to a copying machine as defined in claim 4 wherein said horizontally projecting, elongated plate has a pair of horizontally spaced protuberances on one side thereof, and said horizontal leg has a pair of spaced apertures therein adapted to detachably engage said protuberances in two different positions of said horizontal leg.
 18. An assembly for regulating the feeding of paper to a copying machine as defined in claim 17 wherein said means resiliently retaining said horizontal leg in a selected one of a plurality of positions comprises: a bolt having an end secured to said horizontally projecting elongated plate at a location between said protuberances and projecting downwardly through an opening in said horizontal leg to a bolt head spaced from said horizontal leg; and a helical compression spring around said bolt between the bolt head and horizontal leg.
 19. An assembly for regulating the feeding of paper to a copying machine as defined in claim 1 and further characterized as including means for directing air against the upper end portion of a stack of paper sheets stacked on said feed table for preventing the uppermost sheets in the stack from adhering to each other.
 20. In a duplicating machine having a paper feed table, means for elevating the paper feed table and a stack of paper sheets carried thereon, and means for periodically, and in sequence, feeding paper sheets from the top of the stack into duplicating structure of the machine adapted to form indicia on the sheets, the improvement which comprises: a horizontally extending, elongated slide bar extending transversely across the machine at a level spaced upwardly from the feed table; a clamp structure slidingly mounted on the slide bar for sliding movement therealong; a horizontally extending, elongated plate slidingly extended through the clamp structure in a direction normal to said slide bar and frictionally engaged by said clamp structure; and backstep means pivotally mounted on an end portion of said elongated plate and pivotable through 180* on said elongated plate, said backstep means comprising: an L-shaped supporting plate having a horizontally extending upper leg and a downwardly extending lower leg; and means resiliently retaining said horizontal leg in a selected one of a plurality of positions in juxtaposition to said elongated plate.
 21. The improvement defined in claim 20 wherein said backstep means is further characterized in including an arcuate pressure plate extending in an arc between the lower end of said downwardly extending lower leg and said upper leg.
 22. The improvement defined in claim 20 wherein said means resiliently retaining said horizontal leg in a selected one of a plurality of positions comprises: a bolt having an end secured to said horizontally projecting, elongated plate and projecting downwardly through an opening in said horizontal leg to a bolt head spaced from said horizontal leg; and spring means between the bolt head and the horizontal leg resiliently urging the horizontal leg against said hOrizontally projecting, elongated plate.
 23. The improvement defined in claim 20 and further characterized in including a pair of horizontally spaced protuberances on said horizontally extending, elongated plate engaging mating apertures in the horizontally extending upper leg of said backstep means.
 24. The improvement defined in claim 22 and further characterized as including: a pair of spaced, downwardly projecting hemmispherical protuberances secured to said horizontally projecting, elongated plate at equal distances from, and on opposite sides of, the point of securement of said bolt to said elongated plate; and means in said horizontally extending upper leg detachably engaging said protuberances.
 25. The improvement defined in claim 24 wherein said horizontally extending upper leg has a transverse width substantially equal to the distance between said protuberances, and said bolt opening in said upper leg is located at the midpoint of said transverse width.
 26. The improvement defined in claim 22 wherein said backstep means is further characterized in including an arcuate pressure plate extending in an arc between the lower end of said downwardly extending lower leg and said upper leg.
 27. An assembly for feeding paper stock to a duplicating machine comprising: a paper feed table; means for elevating the paper feed table; a sensing device disposed above the paper feed table for sensing the height of a stack of paper items carried on said paper feed table by contact with the uppermost said paper items; means connected to said table elevating means and responsive to said sensing means for controlling the actuation of said table elevating means in correspondence to the sensed height of said stack of paper items; a plurality of floating vacuum heads positioned over said feed table at a level to engage the uppermost paper item in said stack at a time when the uppermost paper item is sensed by said sensing device, each of said vacuum heads comprising; a vertically extending tubular body having an upper end and a lower end; a sucker tube reciprocably telescoped in said tubular body and having a portion projecting from the lower end of said tubular body; a flexible, elastomeric suction cup attached to the lower end of said sucker tube for engaging, by suction, the uppermost of said paper items; and magnetic engaging means in said tubular body for preventing reciprocation of said sucker tube in said tubular body when said sucker tube is positioned at a selected location in said tubular body; an elongated, horizontally extending air manifold conduit connected at spaced intervals therealong to the upper ends of said tubular bodies; means for oscillating said manifold conduit periodically to displace the uppermost of said paper items into said duplicating machine as said vacuum heads are oscillated with said manifold conduit.
 28. An assembly for feeding paper stock to a duplicating machine comprising: a paper feed table; means for elevating the paper feed table; a sensing device disposed above the paper feed table for sensing the height of the stack of paper items carried on said paper feed table by contact with the uppermost of said paper items, said sensing device comprising: a microswitch assembly including; a microswitch; and an adjustable screw having a part constituting the lowermost portion of the microswitch assembly, and being manually adjustable in its vertical position to facilitate selection of the height of such stack at which the microswitch will be closed when the stack of paper items exceeds said selected height; means connected to said table elevating means and responsive to said sensing means for controlling the actuation of said table elevating means in correspondence to the sensed height of said stack of paper items; a plurality of floating vacuum heads positioned over said feed table at a level to engage the uppermost paper item in Said stack at a time when the uppermost paper item is sensed by said sensing device, each of said floating vacuum heads comprising; a vertically extending tubular body having an upper end and a lower end; a sucker tube reciprocably telescoped in said tubular body and having a portion projecting from the lower end of said tubular body; and a flexible, elastomeric suction cup attached to the lower end of said sucker tube for engaging, by suction, the uppermost of said paper items; an elongated, horizontally extending air manifold conduit connected at spaced intervals therealong to the upper ends of said tubular bodies; and means for oscillating said manifold conduit periodically to displace the uppermost of said paper items into said duplicating machine as said vacuum heads are oscillated with said manifold conduit.
 29. An assembly for regulating the feeding of paper to a copying machine comprising: a paper feed table; means for elevating the paper feed table; a microswitch assembly spaced vertically from, and disposed over, the paper feed table, said microswitch assembly comprising; housing means; a microswitch mounted in the housing means and including a downwardly facing switch contact vertically movable to open and close the microswitch; a spring plate mounted as a cantilever in said housing means, and extending across and touching at a point intermediate its length, said switch contact, for moving the switch contact from a normally open to a closed position when said spring plate is pushed vertically upwardly against said switch contact; and manually adjustable microswitch closing means operatively associated with said microswitch and spring plate in said microswitch assembly for manually selectively adjusting the closure of said microswitch in correlation to the height of a stack of papers on said feed table, said microswitch closing means including contact means projecting downwardly below said spring plate for contact by the uppermost sheet of paper in a stack of paper carried on said feed table; a solenoid connected to said microswitch for actuation when said microswitch is closed; and a mechanical linkage connected between said solenoid and said means for elevating the feed table for inactivating said elevating means when the status of energization of said solenoid is changed.
 30. An assembly for regulating the feeding of paper to a copying machine as defined in claim 29 wherein said microswitch is connected in series with said solenoid, and said assembly is further characterized as including a light connected in parallel with said microswitch and said solenoid whereby said light is illuminated when said microswitch is open and said solenoid is de-energized.
 31. An assembly for regulating the feeding of paper to a copying machine as defined in claim 29 wherein said assembly further includes; a horizontally extending, elongated slide bar extending in a direction transversely of the paper feed table at a location spaced upwardly from the feed table; a clamp structure slidingly mounted on the slide bar for sliding movement in an axial direction therealong; and an elongated plate slidingly extended through the clamp structure in a direction normal to said slide bar and frictionally engaged by said clamp structure, said elongated plate having said housing means detachably mounted at one end thereof disposed over said paper feed table.
 32. An assembly for regulating the feeding of paper as defined in claim 31 wherein said housing means includes: a hollow housing having an upper side and a lower side and having the microswitch mounted therein, said housing having a light aperture in the upper side thereof; a light mounted on said housing adjacent said light aperture; electrical circuitry connected to said microswitch and light for illuminating the light when said microswitch is open; and a closure plate closing the lower side of the housing and having said spring plAte secured to the upper side thereof, said closure plate having an opening therein to accommodate extention therethrough of said contact means.
 33. An assembly for regulating the feeding of paper to a copying machine as defined in claim 29 wherein said means for elevating the paper feed table comprises; an oscillating pawl lever; means connected to said pawl lever and undergoing movement when said pawl lever is oscillated to elevate said feed table; a pawl latch lever pivotally supported for engaging said pawl lever in one position to prevent said pawl lever from oscillating, and for disengaging said pawl lever in a second position to allow said pawl lever to oscillate; and wherein said mechanical linkage includes an adaptor arm having one end connected to said pawl latch lever, and a second end connected to said solenoid for pivoting said pawl latch lever to said one position when said solenoid is energized, and to said second position when said solenoid is de-energized;
 34. An assembly for regulating the feeding of paper to a copying machine as defined in claim 29 wherein said solenoid comprises; a coil; an armature plunger disposed adjacent said coil in a position to reciprocate vertically upon energization and de-energization of said coil; a transverse key secured to said plunger and projecting normal to the direction of reciprocating movement of said plunger, said key supporting said one end of said adapter arm; a solenoid housing containing said coil; a plunger limit plate secured to said housing and projecting downwardly therefrom, said housing and projecting downwardly therefrom, said housing having a vertically extending slot therein receiving said key for limiting the downward movement of said plunger; and a mounting plate connected to said solenoid housing and adapted for securement to said copying machine.
 35. An assembly for regulating the feeding of paper to a copying machine comprising: a paper feed table; means for elevating the paper feed table; a microswitch assembly spaced vertically from, and disposed over, the paper feed table, said microswitch assembly comprising; a housing; a microswitch in said housing; manually adjustable switch closing means selectively adjustable to correlate closing of said microswitch with the height of papers in a stack on said feed table; means movably supporting said microswitch assembly for selective sliding movement thereof in two directions, each extending normal to the vertical direction of elevation of said paper feed table whereby said microswitch assembly can be selectively positioned whereby said microswitch assembly can be selectively positioned relative to a stack of paper items carried on said paper feed table, said movable supporting means comprising; a horizontally extending, elongated slide bar extending in a direction transversely of the paper feed table at a location spaced upwardly from the feed table; a clamp structure slidingly mounted on the slide bar for sliding movement in an axial direction therealong; an elongated plate slidingly extended through the clamp structure in a direction normal to said slide bar and frictionally engaged by said clamp structure, said elongated plate having said housing detachably mounted at one end thereof and disposed over said paper feed table. 